60700 Posted December 8, 2018 Share Posted December 8, 2018 I have a split chassis Ivatt 2-6-2 Bachmann over 15 years old that has recently started to wheel slip mainly on points and gradients. I have bought a new set from Bachmann and installed them but the wheel slip still occurs ,take the body off and all is ok. Could the retaining body screws distort the chassis ? as that is all that I can think is happening. regards Terry Link to post Share on other sites More sharing options...
RMweb Gold The Johnster Posted December 8, 2018 RMweb Gold Share Posted December 8, 2018 It's possible that the wheels are not sitting correctly on the track, and the fact that your problem is related to turnouts and gradients suggests that the loco's weight is not bearing them down on to the railhead properly. I would check the 'set' of the leading and trailing ponies to see that they are not taking too much of the loco's weight, on which it's tractive ability depends. Take the retaining plate off and remove the wheels; you've already replaced them so I know you are comfortable with this. Run a straight edge, metal not card or plastic, along the bottom faces of the split chassis block to ensure that they are level and have not warped due to the dreaded mazak rot, and check that each side is level with the other. Clean the bottom faces of any debris that is hanging around there. Then re-assemble the chassis, ensuring that the retaining plate is sitting properly in position, and test run the loco without the ponies. If your problem is cured you have done two very informative things; you have re-assured yourself that there is no fundamental problem with the mech, and isolated the trouble to the ponies. Check the tightness of their retaining screws, and the brass strip springs on the tops of them, and scrupulously clean their wheels. The ponies need enough vertical play both upwards and downwards to allow the loco to cope with changes in gradients; check that your turnouts are level and not lifting as well, as they sometimes warp around the vee, the most sensitive spot! If the problem is still manifesting itself, then I'm stumped for now, sorry. If you've discovered that the chassis blocks are warped because of mazak rot, the bad news is that the problem will get worse and the loco is doomed; at least 15 years is longer than some of the real ones lasted! Try and get to a show where Tony Wright is running a loco fettling clinic for charity; if he can't fix it, it can't be fixed... But a well run in mechanism doesn't normally give this sort of trouble, which is why I'm drawn to the idea that the ponies are responsible. They need to have vertical play but are lightly sprung with the brass strip springs to avoid bouncing off the road if the going gets a bit rough, so if you are confident of your trackwork it might be worth trying the loco without the brass strips on them to see if that improves matters. Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted December 8, 2018 Share Posted December 8, 2018 Sounds to me that the keeper plate may not be fully home. The carrying wheels on most Bachmann split chassis were oversprung, and it wouldn't take much change in the keeper plate position to have the truck wheels lift the driven wheels just a little too much for effective traction where track isn't quite level. Although I have never had this particular item, if there's one thing I know about Bachmann's split chassis assemblies it is that they are 'tweaky'. So if the checks Johnster suggests reveal nothing amiss, just keep trying assembly adjustents until it comes right. Some of the mechanisms were very sensitive to the keeper plate retaining screws being overtightened: leaving them relatively slack worked best, as an example. Link to post Share on other sites More sharing options...
DCB Posted December 9, 2018 Share Posted December 9, 2018 Bachmann locos often take too much weight on their leading and trailing trucks so it may well be that you have altered the springs when taking the loco apart. Generally worn wheels grip better than new ones, our Bachmann WD doubled its pulling power after being run in. Link to post Share on other sites More sharing options...
60700 Posted December 9, 2018 Author Share Posted December 9, 2018 Thank you all for your feedback to my problem. I have recently changed the coupling on the ponies to Kadee's and as suggested this could have been the problem ,I could not find any Mazak faults and the chassis sits square. The track work is also 20 years old and has never given me any problems apart from two point changes, which are all Peco electrofrog. All other locos perform ok. I have left the two body retaining screws off, and loco has no problem, so I think I am happy with that as points and gradients are no trouble. Thank you again for all your replies. Regards Terry I . Link to post Share on other sites More sharing options...
stevegr Posted December 9, 2018 Share Posted December 9, 2018 I have a split chassis Ivatt 2-6-2 Bachmann over 15 years old that has recently started to wheel slip mainly on points and gradients. I have bought a new set from Bachmann and installed them but the wheel slip still occurs ,take the body off and all is ok. Could the retaining body screws distort the chassis ? as that is all that I can think is happening. regards Terry I think you actually found the problem here. Just do the screws up to hold the body on the chassis. No tighter. Link to post Share on other sites More sharing options...
RMweb Gold The Johnster Posted December 10, 2018 RMweb Gold Share Posted December 10, 2018 I use a cheat which is so bodgeric that I am reluctant to mention it in case somebody thinks I am suggesting it as a serious proposition; it is the absolute antithesis of anything resembling good modelling practice, but has come in useful where I have replaced chassis and mechs with more updated versions whose fixing screws do not line up with the holes on the bodies. I superglue them on with Pound Shop superglue; this is strong enough to hold the body in place and enable you to pick the loco up without it moving about, but can easily be prised off with an old screwdriver if you need to get in there for anything. I am not proud of this, but it may be of some use to you in this case. 2 Link to post Share on other sites More sharing options...
Il Grifone Posted December 10, 2018 Share Posted December 10, 2018 Poundshop superglue isn't much use for anything else! Link to post Share on other sites More sharing options...
RMweb Gold The Johnster Posted December 10, 2018 RMweb Gold Share Posted December 10, 2018 Agreed, but it's perfect for this bodge, or anything you don't want properly glued together... Link to post Share on other sites More sharing options...
60700 Posted December 10, 2018 Author Share Posted December 10, 2018 Thanks Johnster and everybody for their suggestions but i have found the problem which was my own making by fitting Kadees to the ponies the screw holding the Kadee was slightly fouling on the buffer beam causing the chassis to lift slightly, Problem solved. Thank you Terry Link to post Share on other sites More sharing options...
RMweb Gold The Johnster Posted December 11, 2018 RMweb Gold Share Posted December 11, 2018 Glad things have worked out and your Ivatt is back to her full strength! Link to post Share on other sites More sharing options...
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